Today, mobile industry is moving towards smaller and smaller form factors. At the same time, the central processing units (CPUs) of the mobile computing devices are consuming more power, and the thermal cooling is becoming more complex. The CPU peak power requirements are increasing almost exponentially, while the rest of the platform peak power requirements increase.
Another development in the mobile industry is the use of Type C Universal Serial Bus (USB) connectors. The inclusion of Type C USB connectors in mobile platforms means that one connector for designs that are smaller in size must be able to provide 15 W through the USB Type C connector. For example, a mouse connected to the Type C USB port may be recognized as a passive load that requires a lot of power.
Today, some computing platforms are being used with 2S batteries, i.e. batteries which are built of two cells in series (with a possibility of having 2 more in parallel). The reason this battery configuration is used to have a smaller voltage regulator (VR) size, which can be accomplished by having a higher switching frequency. Higher voltages (3S or 4S) are normally reserved for larger systems. Some systems are built with even lower input voltage, with 1 battery cell in series, and 1 or 2 in parallel (1S1P or 1S2P). This is optimized for phones and tablets, and shows switching regulators of particularly low size and high efficiency.
While some computing systems use a 2S configuration, there is interest in moving to a 1S system. Unfortunately, higher peak power requirements for high-performing CPUs make the usage of a 1S battery configuration rather difficult. Such configurations are difficult to implement because systems have a limitation on their minimum input voltage, which is, for example, 2.5V for a 1S system and ˜5.4V for a 2S system. These limitations are driven by the 5V voltage regulator minimum voltage (e.g., 5.4V for a 2S system) and limitations on the use of a power management integrated circuit (PMIC) (e.g., 2.5V for a 1S system, 5.4V for a 2S system). With a higher power jump during certain modes (e.g., CPU Turbo mode) and a power burst of the rest of the platform (ROP) that may possibly accompany the jump in power, it is quite possible that the total system voltage would droop below the minimum allowed system voltage of the computing system. In some systems, this risk requires limiting the peak frequency in a multi-threaded operation, which may negatively affect the performance of the system. It's also understood that when a device (storage, mouse, phone) is connected to a Type C connector, the peak CPU performance may be constrained even further.